1. Field of the Invention
The present invention relates generally to transcutaneous bone conduction devices, and more particularly, to a transcutaneous bone conduction device vibrator having a movable magnetic mass.
2. Related Art
Hearing loss, which may be due to many different causes, is generally of two types: conductive and sensorineural. Sensorineural hearing loss is due to the absence or destruction of the hair cells in the cochlea which transduce sound signals into nerve impulses. Various hearing prostheses are commercially available to provide individuals suffering from sensorineural hearing loss with the ability to perceive sound. For example, cochlear implants include an electrode array for implantation in the cochlea to deliver electrical stimuli to the auditory nerve, thereby causing a hearing percept.
Conductive hearing loss occurs when the normal mechanical pathways which transfer acoustic energy from sound waves to fluid waves in the cochlea are impeded. For example, condsuctive hearing loss may caused by damage to the ossicular chain or ear canal. Individuals suffering from conductive hearing loss may retain residual hearing.
Individuals suffering from conductive hearing loss typically receive a hearing aid. Hearing aids deliver acoustic energy directly to the tympanic membrane, or eardrum. In particular, a conventional hearing aid amplifies received sound and delivers the amplified sound directly to the tympanic membrane via a component positioned in the ear canal or on the pinna. The acoustic energy of the amplified sound ultimately causes motion of the perilymph in the cochlea resulting in stimulation of the auditory nerve.
In contrast to hearing aids, certain types of hearing prostheses, commonly referred to as bone conduction devices, include an actuator that converts received sound into mechanical vibrations. The vibrations are transferred through the skull to the cochlea causing generation of nerve impulses resulting in a hearing perept representative of the received sound.